The present invention relates to an information playback apparatus for playing back information recorded in an information recording medium, such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and an MD (Mini Disc), and more particularly to an information playback apparatus capable of performing random access playback to start playback from an arbitrary portion.
The present application claims priority from Japanese Application No. 2001-321802, the disclosure of which is incorporated herein by reference for all purposes.
As a conventional information playback apparatus for playing back information recorded in an information recording medium, such as a CD, a DVD, and an MD, there is known a type furnished with a random access playback function.
The random access playback function is a function to start information playback by searching a position called a cue point. For example, when the user or the like registers a recording position (address) of desired information as a cue point in advance and specifies the cue point during playback later, he/she can automatically jump to the position of the cue point from a position currently being played back and start information playback from the jumped position.
Besides the random access playback function, a conventional information playback apparatus may be furnished with an editing function for editing information, such as music, recorded in an information recording medium when it is played back, so that a sound at a tempo different from the original music or the like is played. Hence, when the user or the like plays back information, such as music, by using the editing function, he/she can produce various sound effects.
To be more specific, an information playback apparatus furnished with the random access playback function and the editing function is provided with a disc-like rotatable manipulation member called a jog dial. When the user or the like manipulates the jog dial to rotate at a desired speed, a tempo of a playback sound is changed in response to a rotational speed of the jog dial, whereby sound effects at a tempo different from the original music or the like recorded in a CD, a DVD, etc. can be produced.
In other words, it is known that by forcedly rotating the turntable of an analog record player, on which is placed an analog record, such as an LP, at the number of revolutions (rotational speed) different from the normal number of revolutions while the analog record is being played, the moving speed (running speed) of the stylus moving in the recording grooves of the analog record is changed, thereby producing a sound at a tempo different from the originally played back music or the like. For example, it is known that if an analog record having recorded slow-tempo music is played forcedly at a higher number of revolutions than the normal number of revolutions, music is played as if it were up-tempo music.
The jog dial is provided to the conventional information playback apparatus to attain the same phenomenon as with the analog record player.
The jog dial is provided as an equivalent to the turntable of the analog record player, and when the user or the like changes the rotational speed of the jog dial by hand, he/she can produce the same sound effects produced when forcedly changing the moving speed of the stylus with respect to an analog record, that is, sound effects at a tempo different from the original music or the like.
Further, the user or the like can achieve complicated and sophisticated editing by making full use of the random access playback function and the editing function. He/she can perform editing in various manners by, for example, producing sound effects at different tempos by manipulating the jog dial while a given portion of music is being played, then manipulating the jog dial further while music is being played from a desired portion by the random access playback function, whereby he/she can produce sound effects by playing the desired portion at different tempos.
As has been described, the conventional information playback apparatus furnished with the random access playback function and the editing function is provided with multiple functions, so that it can be used not only as a music player, but also as an electronic musical instrument.
However, the conventional information playback apparatus furnished with the random access playback function and the editing function has a problem that when access is made to a cue point position different from a given portion of music currently being played and playback is continued, a discontinuous sound is played at the beginning of the random access playback.
To be more concrete, as shown in FIG. 8(a), in a case where music recorded in an information recording medium, such as a CD or a DVD, is composed of a slow-tempo portion (a portion at a slow tempo) and an up-tempo portion (a portion at a fast tempo), if the up-tempo portion is registered as a cue point (register an address ADR2) in advance, and the cue point is specified at a given time point tc (a time point corresponding to an address ADR1) while the slow-tempo portion is being played back, information playback is continued by jumping from the address ADR1 to the address ADR2.
In this case, as shown in FIG. 8(b), a tempo of the music played before the time point tc is slow and fast after the time point tc, which poses a problem that a discontinuous harsh sound is played at the time point tc.
Also, when the cue point is specified, there may be a time delay until the pickup serving as information readout means moves to the address ADR2, which poses a problem that a harsh sound is played or so-called cut-off of a sound occurs.
Further, in the case of an information recording medium having recorded slow-tempo music and up-tempo music, when the slow-tempo music currently being played is switched to the up-tempo music registered as a cue point in advance, there also arises a problem that a discontinuous harsh sound is played or cut-off of a sound occurs.
When such a harsh sound is played or cut-off of a sound occurs, there arises an inconvenience as follows. That is, the conventional information playback apparatus is used in a discotheque or the like, where a manipulator called a disc jockey creates an enjoyable mood for those who are dancing to the music by instantly performing rap music or the like with the random access playback function and the editing function. However, if the aforementioned harsh sound is played or cut-off of a sound occurs when access is made to the start position of the information playback by the random access playback function, there arises an inconvenience that the disc jockey cannot provide enjoyable dance music which sounds natural.